Sample size estimate: Based on our previous studies (Juon et al. 2008; Hsu et al. 2007), the investigators estimate that about 10% of all the participants will test hepatitis B virus (HBV) positive, 40 to 50% will be HBV negative but protected, and about 50% will be unprotected. In the preliminary analysis of R25, there were significant mean differences of knowledge of HBV transmission (score ranged 0-10) in intervention (7.21±1.83SD) and control group (5.54±2.07SD) in post-test. The investigators estimated our sample size to be 50 in each intervention and control group among those unprotected. Assuming a conservative rate of attrition about 20%, the investigators calculated the study power based on sample size at follow-up. The sample size of 50 at pre-test is to detect mean difference in knowledge outcome at 96% power (1-β) and type I error of 0.05.Thus, our proposed sample size (n=50) for each group among those unprotected has sufficient power. Our total sample size is 600 (50/group x 2 groups x 2 (infected and protected-50% of study population) x 3 ethnic groups).